Over a 5-year period, all retroperitoneal soft tissue sarcomas (119) referred to the Royal Marsden Hospital, London, U.K., were recorded prospectively on a database and managed with a consistent treatment policy. On multivariate analysis, the significant factors responsible for determining prognosis were grade and completeness of excision. Despite improvements in surgical clearance rates (nearly 50% completely excised in this series), the prognosis was poor with 2- and 5-year survival rates of 53 and 20%, respectively. Further improvements in survival rates will depend on better adjuvant treatment.